Amorphous alloy ribbon

ABSTRACT

The invention provides an amorphous alloy ribbon consisting of Fe, Si, B, C, and unavoidable impurities, in which a content of Si is from 8.5 atom % to 9.5 atom %, and a content of B is from 10.0 atom % to less than 12.0 atom % when a total content of Fe, Si, and B is 100.0 atom %, a content of C relative to the total content of 100.0 atom % is from 0.2 atom % to 0.6 atom %, and the ribbon has a thickness of from 10 μm to 40 μm and a width of from 100 mm to 300 mm.

TECHNICAL FIELD

The present invention relates to an amorphous alloy ribbon.

BACKGROUND ART

An amorphous alloy ribbon is regarded as a promising industrial material for various end uses because of its superb characteristics.

Among others, an Fe-base amorphous alloy ribbon containing Fe (iron) as a main component (for example, an Fe—B—Si-base amorphous alloy ribbon containing Fe (iron) as a main component, and additionally B (boron) and Si (silicon)) has been used as a material for a transformer core or the like, because of low core loss, high saturation magnetic flux density, and the like. Since such an Fe-base amorphous alloy ribbon has a space factor generally lower than a grain-oriented electrical steel sheet, a higher space factor has been desired in the Fe-base amorphous alloy ribbon. In a case in which a space factor is low and a core is produced with the same outer and inner diameters, the total magnetic flux and the inductance are decreased, and consequently it becomes necessary to increase the core size or winding number in order to compensate, which conflicts with the downsizing of a device and cost reduction.

Various investigations have been carried out for improvement of the space factor of an Fe-base amorphous alloy ribbon.

For example, as a method for producing an Fe-base amorphous alloy ribbon having a high space factor by a single-roll method, a method of adjusting production conditions, such as a distance between a molten metal nozzle tip and a chill roll surface, the temperature of a chill roll, the circumferential speed of a chill roll, the surrounding atmosphere of a chill roll, the extrusion pressure of a molten metal nozzle, or a surface condition of a chill roll, is known (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2006-281317, JP-A No. H9-216036, or JP-A No. 2007-217757).

SUMMARY OF INVENTION Technical Problem

However, by a method for improving the space factor of a ribbon by adjusting production conditions as in the case of the conventional art described above, it may be occasionally difficult to maintain a production condition (for example, a surface condition of a chill roll) for a long time period, when an amorphous alloy ribbon is produced continuously. Further, in the case of a method for improving the space factor of a ribbon by adjusting production conditions, a magnetic property such as a magnetic flux density is occasionally lowered.

Therefore, as a method for improving the space factor of an Fe—B—Si-base amorphous alloy ribbon, a method of adjusting, in addition to the production conditions, also the composition itself of an Fe—B—Si-base amorphous alloy ribbon, is conceivable.

From the investigations of the present inventors, it became clear that the space factor of a ribbon could be improved by adding C (carbon) to the composition of an Fe—B—Si-base amorphous alloy ribbon. As the result of additional investigations it became clear that, in a case in which C is added excessively to an Fe—B—Si-base amorphous alloy ribbon with a relatively high content of Si, the ribbon tends to become brittle.

Further, it is also important to maintain a high magnetic flux density in an amorphous alloy ribbon.

Accordingly, an object of the invention is to provide an amorphous alloy ribbon with a superior space factor, in which brittleness is suppressed and which has a magnetic flux density that is maintained at a high level.

Solution to Problem

Specific means for attaining the object are as follows.

-   <1>An amorphous alloy ribbon consisting of Fe, Si, B, C, and     unavoidable impurities, wherein: a content of Si is from 8.5 atom %     to 9.5 atom %, and a content of B is from 10.0 atom % to less than     12.0 atom % when a total content of Fe, Si, and B is 100.0 atom %, a     content of C relative to the total content of 100.0 atom % is from     0.2 atom % to 0.6 atom %, and the ribbon has a thickness of from 10     μm to 40 μm and a width of from 100 mm to 300 mm. -   <2>The amorphous alloy ribbon according to <1>, wherein the content     of C is from 0.3 atom % to 0.6 atom %. -   <3>The amorphous alloy ribbon according to <1>or <2>, wherein the     content of B is from 10.0 atom % to 11.5 atom %. -   <4>The amorphous alloy ribbon according to any one of <1>to <3>,     wherein a space factor is 88% or more. -   <5>The amorphous alloy ribbon according to any one of <1>to <4>,     wherein a content of Fe is from 79.0 atom % to 80.0 atom %, a     content of Si is from 8.5 atom % to 9.5 atom %, and a content of B     is from 10.5 atom % to 11.5 atom % when a total content of Fe, Si,     and B is 100.0 atom %. -   <6>The amorphous alloy ribbon according to any one of <1>to <5>,     which is produced by a single-roll method.

Advantageous Effects of Invention

The invention can provide an amorphous alloy ribbon with a superior space factor, in which brittleness is suppressed and which has a magnetic flux density that is maintained at a high level.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual schematic cross-sectional view of an embodiment of an amorphous alloy ribbon production apparatus appropriate for production of an amorphous alloy ribbon according to the invention.

FIG. 2 is a schematic view of a sample used for evaluation of brittleness.

FIG. 3 is a conceptual schematic view of a sample piece and a tear line after tearing for evaluation of brittleness.

DESCRIPTION OF EMBODIMENTS

A numerical range expressed by “from x to y” includes herein the values of x and y in the range as the minimum and maximum values, respectively.

An amorphous alloy ribbon according to the invention will be described below in detail.

An amorphous alloy ribbon according to the invention (hereinafter also referred to simply as a “ribbon”) consists of Fe, Si, B, C, and unavoidable impurities, and the content of Si is from 8.5 atom % to 9.5 atom % (in other words, not less than 8.5 atom % and not more than 9.5 atom %), and the content of B is from 10.0 atom % to less than 12.0 atom % when the total content of Fe, Si, and B is 100.0 atom %, and the content of C relative to the total content of 100.0 atom % is from 0.2 atom % to 0.6 atom % (in other words, not less than 0.2 atom % and not more than 0.6 atom %), and the ribbon has a thickness of from 10 μm to 40 μm (in other words, not less than 10 μm and not more than 40 μm), and a width of from 100 mm to 300 mm (in other words, not less than 100 mm and not more than 300 mm)

According to investigations by the inventors, it became clear that when C (carbon) is added to the composition of an Fe—B—Si-base amorphous alloy ribbon containing Fe as a main component, and further containing B and Si (hereinafter also referred to simply as an “Fe—B—Si-base amorphous alloy ribbon”), the space factor of the ribbon can be improved. This is presumably because the flowability of a molten alloy, which is a source material for an Fe—B—Si-base amorphous alloy ribbon, is increased by addition of C, and as the result the surface flatness of a ribbon product is improved.

As the result of additional investigations by the inventors it became clear that when the amount of C added to an Fe—B—Si-base amorphous alloy ribbon with a composition containing a relatively large amount of Si (specifically, the content of Si being 8.5 atom % or more when the total content of Fe, Si, and B is 100.0 atom %) is excessive (specifically, the content of C is more than 0.6 atom % relative to the total content of Fe, Si, and B of 100.0 atom %), the ribbon becomes brittle.

Further, the inventors found that by adding C to a composition for an Fe—B—Si-base amorphous alloy ribbon having a Si content of 8.5 atom % or more when the total content of Fe, Si, and B is 100.0 atom %, at a content of from 0.2 atom % to 0.6 atom % with respect to the total amount of 100.0 atom %, the space factor can be improved while suppressing the brittleness and, moreover, a high magnetic flux density can be maintained, and completed the invention based on these findings.

That is, the invention provides an amorphous alloy ribbon with a superior space factor, in which brittleness is suppressed and which has a magnetic flux density that is maintained at a high level.

Further according to the invention, by limiting the content of C to 0.6 atom % or less, aging deterioration of an amorphous alloy ribbon, which may appear when C is added, can be suppressed.

As described above, an amorphous alloy ribbon according to the invention exhibits a high space factor (for example, space factor of 86% or more).

The space factor of an amorphous alloy ribbon according to the invention is preferably 88% or more, and more preferably 89% or more.

“Space factor” means herein a space factor (%) measured according to ASTM A900/A900M-01 (2006).

In this connection, when a transformer core is produced with an amorphous alloy ribbon having a space factor of 88% according to the measurement method, it is empirically known that the space factor may be slightly increased by clamping during production to exhibit a space factor of the product core of from 88 to 90%.

A composition of an amorphous alloy ribbon according to the invention will be described below.

The content of C in an amorphous alloy ribbon according to the invention based on the total content of Fe, Si, and B as 100.0 atom % (hereinafter also referred to simply as “content of C”) is from 0.2 atom % to 0.6 atom %.

When the content of C exceeds 0.6 atom %, a ribbon becomes brittle. Further, when the content of C exceeds 0.6 atom %, aging deterioration of an amorphous alloy ribbon may be promoted and the time until occurrence of crystallization may be shortened.

Meanwhile, when the content of C is 0.2 atom % or more in the invention, this indicates that C is substantially contained in a ribbon, and that the space factor of the ribbon can be improved accordingly.

From a viewpoint of improvement of the space factor of a ribbon, the content of C is preferably from 0.3 atom % to 0.6 atom %.

The content of Si in an amorphous alloy ribbon according to the invention based on the total content of Fe, Si, and B as 100.0 atom % (hereinafter also referred to simply as “content of Si”) is from 8.5 atom % to 9.5 atom %.

When the content of Si in an amorphous alloy ribbon according to the invention is from 8.5 atom % or more, a suppression effect on aging deterioration of the ribbon can be expected. The content of Si is more preferably 9.0 atom % or more.

However, as described above, it has become clear that, in a case in which C is added excessively to an Fe—B—Si-base amorphous alloy ribbon with a content of Si of 8.5 atom % or more (especially 9.0 atom % or more), the ribbon tends to become brittle. In regard to this point, the content of C is limited to 0.6 atom % or less in an amorphous alloy ribbon according to the invention, so that the brittleness of the ribbon is suppressed remarkably.

On the other hand, when the content of Si exceeds 9.5 atom %, the content of Fe becomes relatively low and the saturation magnetic flux density decreases. Further, when the content of Si exceeds 9.5 atom %, the amorphization ability tends to decrease.

The content of B in an amorphous alloy ribbon according to the invention based on the total content of Fe, Si, and B as 100.0 atom % (hereinafter also referred to simply as “content of B”) is from 10.0 atom % to less than 12.0 atom % (preferably from 10.0 atom% to 11.5 atom %).

When the content of B is less than 10.0 atom %, the crystallization temperature becomes low and the stability of an amorphous phase is impaired.

On the other hand, when the content of B is 12.0 atom % or more, it is not preferable because the cost of source materials increases. Therefore, the content of B is less than 12.0 atom %, but preferably 11.5 atom % or less.

From a viewpoint of improvement of amorphization ability, the content of B is preferably 10.5 atom % or more, and more preferably 11.0 atom % or more.

There is no particular restriction on the content of Fe in an amorphous alloy ribbon according to the invention based on the total content of Fe, Si, and B as 100.0 atom % (hereinafter also referred to simply as “content of Fe”), insofar as the content of Si is from 8.5 atom % to 9.5 atom %, and the content of B is from 10.0 atom % to less than 12.0 atom %.

Specifically, the content of Fe is more than 78.5 atom % but not more than 81.5 atom %, preferably from 79.0 atom % to 81.5 atom %, more preferably from 79.0 atom % to 81.0 atom %, further preferably from 79.0 atom % to 80.5 atom %, and especially preferably from 79.0 atom % to 80.0 atom %.

When the content of Fe is 81.0 atom % or less, the crystallization temperature becomes higher and the thermal stability is improved.

According to the invention, a preferable combination of contents of Fe, Si, and B is a combination of the content of Fe from 79.0 atom % to 81.5 atom % (more preferably from 79.0 atom % to 81.0 atom %, further preferably from 79.0 atom % to 80.5 atom %), the content of Si from 8.5 atom % to 9.5 atom %, and the content of B from 10.0 atom % to less than 12.0 atom % (preferably from 10.0 atom % to 11.5 atom %); a more preferable combination is a combination of the content of Fe from 79.0 atom % to 80.0 atom %, the content of Si from 8.5 atom % to 9.5 atom %, and the content of B from 10.5 atom % to 11.5 atom %; and an especially preferable combination is a combination of the content of Fe from 79.0 atom % to 80.0 atom %, the content of Si from 9.0 atom % to 9.5 atom %, and the content of B from 11.0 atom % to 11.5 atom %.

An amorphous alloy ribbon according to the invention also contains unavoidable impurities in addition to the above elements (Fe, Si, B, and C). In this regard, unavoidable impurities refer to impurities that are unavoidably mixed in during a production process of an amorphous alloy ribbon, or during a production process of a mother alloy or a molten alloy, which are source materials for the ribbon. Examples of the unavoidable impurities include Mn, S, Cr, P, Ti, Ni, Al, Co, Zr, Mo, and Cu.

However, physical properties of an amorphous alloy ribbon are dominantly decided by Si and B, and influence of the impurities is minimal

The thickness (web thickness) of an amorphous alloy ribbon according to the invention is from 10 μm to 40 μm.

When the thickness is less than 10 μm, the mechanical strength of a ribbon tends to become insufficient. From this viewpoint the thickness is 10 μm or more, preferably 15 μm of more, and more preferably 20 μm or more.

Meanwhile, when the thickness exceeds 40 μm, it tends to become difficult to obtain stably an amorphous phase. Although from this viewpoint the thickness is 40 μm or less, the thickness is preferably 35 μm or less, and more preferably 30 μm or less.

The width of an amorphous alloy ribbon according to the invention is from 100 mm to 300 mm.

When the width is 100 mm or more, a practical transformer can be produced favorably. Although from this viewpoint the width is 100 mm or more, the width is more preferably 125 mm or more.

Meanwhile, when the width exceeds 300 mm, it becomes difficult to obtain a ribbon having uniform thickness in the width direction, and due to the uneven form, partial embrittlement or a decrease in a magnetic flux density (B1) may occur. Although from this viewpoint the width is 300 mm or less, it is more preferably 275 mm or less.

There is no particular restriction on a production method of an amorphous alloy ribbon according to the invention, and a publicly known method such as a liquid quenching method (a single-roll method, a twin-roll method, a centrifugation method, or the like) can be applied.

Among these, a single-roll method is a production method, in which production equipment is relatively simple, and stable production is possible, and has excellent industrial productivity.

FIG. 1 is a conceptual schematic cross-sectional view of an embodiment of an amorphous alloy ribbon production apparatus appropriate for production of an amorphous alloy ribbon according to the invention.

An amorphous alloy ribbon production apparatus 100 shown in FIG. 1 is an amorphous alloy ribbon production apparatus based on a single-roll method.

As shown in FIG. 1, the amorphous alloy ribbon production apparatus 100 is provided with a crucible 20 provided with a molten metal nozzle 10, and a chill roll 30, a surface of which faces a tip of the molten metal nozzle 10. FIG. 1 is a cross-sectional view of the amorphous alloy ribbon production apparatus 100 sectioned by a plane perpendicular to the axis direction of the chill roll 30 and to the width direction of an amorphous alloy ribbon 22C (the two directions are identical).

The crucible 20 has an internal space that can accommodate a molten alloy 22A, which is a source material for an amorphous alloy ribbon, and the internal space is communicated with a molten metal flow channel in a molten metal nozzle 10. As a result, a molten alloy 22A accommodated in the crucible 20 can be discharged through the molten metal nozzle 10 to a chill roll 30 (in FIG. 1, the discharge direction and the flow direction of the molten alloy 22A is represented by the arrow Q). A crucible 20 and a molten metal nozzle 10 may be configured as an integrated body or as separate bodies.

At least partly around a crucible 20, a high-frequency coil 40 is placed as a heating means. By this, a crucible 20 in a state accommodating a mother alloy of an amorphous alloy ribbon can be heated to form a molten alloy 22A in the crucible 20, or a molten alloy 22A supplied from the outside to the crucible 20 can be kept in a liquid state.

A molten metal nozzle 10 has an opening for discharging a molten alloy (a discharge port).

It is appropriate that the opening is a rectangular (slit shape) opening. The length of a long side of a rectangular opening corresponds to the width of an amorphous alloy ribbon to be produced. Specifically, the length of a long side of a rectangular opening is preferably from 100 mm to 300 mm. The lower limit of the length of a long side is more preferably 125 mm. The upper limit of the length of a long side is more preferably 275 mm.

The distance between a tip of a molten metal nozzle 10 and a surface of a chill roll 30 is so small, that, when a molten alloy 22A is discharged through a molten metal nozzle 10, a puddle 22B of a molten alloy 22A is formed.

Although the distance may be in a range ordinarily set for a single-roll method, it is preferably 500 μm or less, and more preferably 300 μm or less.

Further, from a viewpoint of suppression of contact between a tip of a molten metal nozzle 10 and a surface of a chill roll 30, the distance is preferably 50 μm or more.

A chill roll 30 is configured such that it rotates axially to the direction of the arrow P.

A cooling medium such as water is circulated inside a chill roll 30, with which a molten alloy 22A coated (discharged) on a surface of a chill roll 30 can be cooled to form an amorphous alloy ribbon 22C.

The material of a chill roll 30 is preferably a material having high thermal conductivity, such as Cu, or a Cu alloy (a Cu—Be alloy, a Cu—Cr alloy, a Cu—Zr alloy, a Cu—Zn alloy, a Cu—Sn alloy, a Cu—Ti alloy, or the like).

Although there is no particular restriction on the surface roughness of a surface of a chill roll 30, from a viewpoint of a space factor, the arithmetic average roughness (Ra) of a surface of a chill roll 30 is preferably 0.5 μm or less, and more preferably 0.3 μm or less. The arithmetic average roughness (Ra) of a surface of a chill roll 30 is preferably 0.1 μm or more from a viewpoint of processability for adjustment of the surface roughness.

Further, in the embodiment, a surface of a chill roll 30 may be polished by a brush or the like during production of an alloy ribbon in order to keep the preferable surface roughness (Ra).

Meanwhile, as a chill roll 30 a chill roll ordinarily used in a single-roll method may be used.

From a viewpoint of cooling power, the diameter of a chill roll 30 is preferably 200 mm or more, and more preferably 300 mm or more. Meanwhile, from a viewpoint of cooling power, the diameter is 700 mm or less.

The surface roughness (the arithmetic average roughness Ra) means herein surface roughness measured according to JIS B 0601 (2001).

Close to a surface of a chill roll 30 (downstream of a molten metal nozzle 10 in the rotational direction of a chill roll 30), a peeling gas nozzle 50 is placed. This blows a peeling gas (for example, a nitrogen gas, or a high pressure gas such as compressed air) in the direction (the direction of a dashed line arrow in FIG. 2) opposite to the rotational direction of a chill roll 30 (arrow P), such that peeling of an amorphous alloy ribbon 22C from a chill roll 30 can be performed more efficiently.

An amorphous alloy ribbon production apparatus 100 may be provided with another component in addition to the above components (for example, a wind-up roll for reeling up a produced amorphous alloy ribbon 22C, or a gas nozzle for blowing a CO₂ gas, a N₂ gas, or the like to a puddle 22B of a molten alloy or its vicinity).

Further, a basic configuration of an amorphous alloy ribbon production apparatus 100 may be similar to a configuration of an amorphous alloy ribbon production apparatus based on a conventional single-roll method (for example, see Japanese Patent No. 3494371, Japanese Patent No. 3594123, Japanese Patent No. 4244123, and Japanese Patent No. 4529106).

Next, an example of production of an amorphous alloy ribbon 22C using an amorphous alloy ribbon production apparatus 100 will be described.

A molten alloy 22A as a source material for an amorphous alloy ribbon according to the invention is prepared in a crucible 20.

In this connection, the molten alloy 22A may be a molten alloy obtained by melting a mother alloy with the composition of an amorphous alloy ribbon according to the invention, or a molten alloy obtained by firstly preparing a mother alloy of a composition equivalent to that of an amorphous alloy ribbon according to the invention excluding C (carbon), and then dissolving C (carbon) in the molten metal of the mother alloy.

Although there is no particular restriction on the temperature of a molten alloy 22A, from a viewpoint of suppression of adhesion of a precipitate originated from a molten alloy 22A on to a wall surface of a molten metal nozzle, the temperature is preferably 1210° C. or more, and more preferably 1260° C. or more. Further, from a viewpoint of suppression of formation of an air pocket to be formed on the side of a contact surface with a surface of a chill roll 30, the temperature of a molten alloy 22A is preferably 1410° C. or less, and more preferably 1360° C. or less.

Next, a molten alloy is discharged through a molten metal nozzle 10 onto a surface of a chill roll 30 rotating in the direction of the arrow P, while forming a puddle 22B, to form a coated film of the molten alloy on the surface of a chill roll 30, and the coated film is cooled to form an amorphous alloy ribbon 22C. Then the amorphous alloy ribbon 22C formed on the surface of a chill roll 30 is peeled from the surface of a chill roll 30 by blowing a peeling gas from a peeling gas nozzle 50 and reeled up on a wind-up roll (not illustrated) in a form of a roll for recovery.

Operations from discharging of a molten alloy to reeling-up (recovery) of an amorphous alloy ribbon are carried out continuously, and as the result, a long amorphous alloy ribbon having, for example, a longitudinal direction length of 3000 m or more can be obtained.

In this case, the discharge pressure of a molten alloy is preferably 10 kPa or more, and more preferably 15 kPa or more. Meanwhile, the discharge pressure is preferably 30 kPa or less, and more preferably 25 kPa or less.

When the discharge pressure is within the preferable range, the space factor can be further improved.

The rotation speed of a chill roll 30 may be in a range ordinarily set for a single-roll method, and a circumferential speed of 40 m/s or less is preferable, and a circumferential speed of 30 m/s or less is more preferable. Meanwhile, the rotation speed in terms of a circumferential speed of 10 m/s or more is preferable, and a circumferential speed of 20 m/s or more is more preferable.

The temperature of a surface of a chill roll 30 after elapse of 5 sec or more from the initiation of a supply of a molten alloy onto a surface of a chill roll 30 is preferably 80° C. or more, and more preferably 100° C. or more. Meanwhile, the temperature is preferably 300° C. Of less, and more preferably 250° C. or less.

The cooling rate of a molten alloy by a chill roll 30 is preferably 1×10⁵° C./s or more, and more preferably 1×10⁶° C./s or more.

EXAMPLES

The invention will be described specifically blow by way of Examples, provided that the invention is not limited to the Examples. In Examples, “at %” represents atom %.

[Examples 1 to 9, Comparative Examples 1 and 2] <<Production of Amorphous Alloy Ribbon>>

An amorphous alloy ribbon production apparatus configured similarly to the amorphous alloy ribbon production apparatus 100 in FIG. 1 was prepared. As a chill roll, the following chill roll was prepared.

Chill Roll

-   Material: Cu—Be alloy -   Diameter: 400 mm -   Arithmetic average roughness Ra of chill roll surface: 0.3 μm

A molten alloy composed of Fe, Si, B, C, and unavoidable impurities (hereinafter also referred to as an “Fe—Si—B—C-base molten alloy”) was prepared in a crucible. More particularly, a mother alloy composed of Fe, Si, B, and unavoidable impurities was melted, and carbon was added to the obtained molten metal, and melted and mixed to prepare a molten alloy for producing an amorphous alloy ribbon as shown in Table 1 below.

Next, the Fe—Si—B—C-base molten alloy was discharged from a molten metal nozzle having a rectangular (slit shape) opening with a long side length of 142 mm and a short side length of 0.6 mm, through the opening onto a surface of a rotating chill roll for rapid solidification to produce 1000 kg of an amorphous alloy ribbon having a width of 142 mm and a thickness of 25 μm.

Detailed production conditions of an amorphous alloy ribbon were as follows.

-   Discharge pressure of molten alloy: 20 kPa -   Circumferential speed of chill roll: 25 m/s -   Temperature of molten alloy: 1300° C. -   Distance between molten metal nozzle tip and chill roll surface: 200     μm -   Cooling temperature (a temperature after elapse of 5 sec or more     from the initiation of a supply of the molten alloy onto a surface     of the chill roll): 170° C.

The contents of Fe, Si, B, and C in an amorphous alloy ribbon in each of Examples and Comparative Examples are as shown in Table 1 below.

In Table 1, the content of Fe (atom %), the content of Si (atom %), and the content of B (atom %) are respectively based on a total content of Fe, Si, and B of 100.0 atom %. The content of C (atom %) is based on the total content of Fe, Si, and B of 100.0 atom % (in other words, an addition amount of C with respect to the total content of 100.0 atom %).

The contents were measured by inductively coupled plasma atomic emission spectrophotometry.

<<Evaluation>>

An amorphous alloy ribbon in each Example and Comparative Example was evaluated as follows.

<Space Factor>

With respect to an amorphous alloy ribbon in each Example and Comparative Example, the space factor (%) was measured according to ASTM A900/A900M-01 (2006).

The measurement results are shown in Table 1 below.

<Brittleness>

With respect to an amorphous alloy ribbon in each Example and Comparative Example, the brittleness was evaluated as follows (quantification of brittleness).

The brittleness values obtained by the evaluation are shown in Table 1 below. With respect to the evaluation result, a lower brittleness value means better suppression of brittleness, and a higher brittleness value means severer brittleness.

Evaluation of brittleness will be described referring to FIG. 2 and FIG. 3.

FIG. 2 is a schematic view of a sample used for evaluation of brittleness, and FIG. 3 is a conceptual schematic view of a sample piece and a tear line after tearing for evaluation of brittleness.

An evaluation of brittleness was performed such that a sample having a length of 1250 mm (equivalent to the circumference of the chill roll) was cut out from an amorphous alloy ribbon as shown in FIG. 2, the sample was bisected with respect to the longitudinal direction (cut at the position of the dot-dash line in FIG. 2) to yield 2 sample pieces, and the sample pieces were used for the evaluation.

Specifically, with respect to each sample piece, a longitudinal end of the sample piece was notched as a tear starting point, and a tearing manipulation of applying a shear force to the sample piece was conducted (the manipulation is hereinafter referred to as “tearing manipulation”). The tearing manipulation was carried out along the longitudinal direction of a sample piece from a longitudinal end to the other longitudinal end. The tearing direction at a tearing manipulation is shown in FIG. 3 as the arrow R.

Next, a tear line formed actually by the tearing manipulation (for example, the tear line T in FIG. 3) was observed visually for examining the number of steps of 6 mm or more in the width direction of the sample piece generated in the tear line (a step with a height k of 6 mm or more in FIG. 3).

Based on the results, brittleness with respect to a tear line was evaluated according to the following evaluation criterion.

With respect to the following evaluation criterion, grade 1 means brittleness being suppressed maximally, and grade 5 means maximally brittle.

Evaluation Criterion for Brittleness per Tear Line

-   Grade 1:The number of steps of 6 mm or more per tear line is 0. -   Grade 2:The number of steps of 6 mm or more per tear line is from 1     to 3. -   Grade 3:The number of steps of 6 mm or more per tear line is from 4     to 6. -   Grade 4:The number of steps of 6 mm or more per tear line is from 7     to 9. -   Grade 5:The number of steps of 6 mm or more per tear line is 10 or     more, (or the sample piece was destroyed by a tearing manipulation     such that tear of the sample piece in the longitudinal direction     could not be substantially performed).

The evaluation of brittleness per tear line was conducted for each of: the center in the width direction, a position 6.4 mm from a width-direction end of a sample piece (2 sides), and a position 12.8 mm from a width-direction end of a sample piece (2 sides) as shown in FIG. 2. The valuation positions are shown in FIG. 2 as dashed lines. There are 5 evaluation positions in each of bisected sample pieces, and therefore there are 10 positions per each sample. In other words, there are 10 tear lines per sample.

Next, from evaluation results of 10 tear lines, an average value of brittleness was calculated and the obtained average value was used as the brittleness value of the sample.

<Magnetic Flux Density (B1, 60 Hz)>

A magnetic flux density (B1, 60 Hz) was measured for an amorphous alloy ribbon of each Example and Comparative Example according to ASTM A932/A932M-01 by applying a magnetic field of frequency 60 Hz and 79.557 A/m.

The measurement results are shown in the following Table 1.

TABLE 1 Evaluation result Amorphous alloy ribbon Magnetic Content of Fe, Si, and B Space flux (at %) Content of C factor density Fe Si B Fe + Si + B (at %) (%) Brittleness (T) Example 1 79.5 9.2 11.3 100.0 0.2 86.2 1.4 1.505 Example 2 79.3 9.3 11.4 100.0 0.3 88.1 1.4 1.506 Example 3 79.4 9.2 11.4 100.0 0.5 89.8 1.0 1.521 Example 4 79.3 9.3 11.4 100.0 0.6 89.3 1.5 1.515 Example 5 79.5 9.2 11.3 100.0 0.3 88.3 1.1 1.504 Example 6 79.5 9.1 11.4 100.0 0.3 88.3 1.4 1.527 Example 7 79.3 9.2 11.5 100.0 0.3 88.4 1.3 1.502 Example 8 79.4 9.1 11.5 100.0 0.3 88.4 1.0 1.517 Example 9 79.1 9.4 11.5 100.0 0.3 88.1 1.0 1.513 Comparative 79.4 9.3 11.3 100.0 0.7 89.0 4.0 1.512 Example 1 Comparative 79.4 9.2 11.4 100.0 1.1 89.1 4.4 1.508 Example 2

Remarks on Table 1

The content of Fe (at %), the content of Si (at %), and the content of B (at %) are respectively based on the total content of Fe, Si, and B as 100.0 at %.

The content of C (at %) is based on the total content of Fe, Si, and B as 100.0 at % (in other words, an addition amount of C with respect to the total content of Fe, Si, and B as 100.0 at %).

A smaller brittleness value means better suppression of brittleness, and a larger value means severer brittleness.

As shown in Table 1, with respect to Examples 1 to 9, where the contents of C are from 0.2 at % to 0.6 at %, the space factor was superior, the brittleness was suppressed, and a high magnetic flux density was maintained. Especially, with respect to Examples 2 to 9, where the the contents of C were from 0.3 atom % to 0.6 atom %, it was confirmed that the space factor was 88% or more.

Meanwhile, in Comparative Examples 1 and 2, where the contents of C were beyond 0.6 atom %, the brittleness was deteriorated.

The entire contents of the disclosure by Japanese Patent Application No. 2012-058714 are incorporated herein by reference.

All the document, patent document, and technical standards cited herein are also herein incorporated by reference to the same extent as provided for specifically and severally with respect to an individual document, patent document, and technical standard to the effect that the same should be so incorporated by reference. 

1. An amorphous alloy ribbon consisting of Fe, Si, B, C, and unavoidable impurities, wherein: a content of Si is from 8.5 atom % to 9.5 atom %, and a content of B is from 10.0 atom % to less than 12.0 atom % when a total content of Fe, Si, and B is 100.0 atom %, a content of C relative to the total content of 100.0 atom % is from 0.2 atom % to 0.6 atom %, and the ribbon has a thickness of from 10 μm to 40 μm and a width of from 100 mm to 300 mm.
 2. The amorphous alloy ribbon according to claim 1, wherein the content of C is from 0.3 atom % to 0.6 atom %.
 3. The amorphous alloy ribbon according to claim 1, wherein the content of B is from 10.0 atom % to 11.5 atom %.
 4. The amorphous alloy ribbon according to claim 1, wherein a space factor is 88% or more.
 5. The amorphous alloy ribbon according to claim 1, wherein a content of Fe is from 79.0 atom % to 80.0 atom %, a content of Si is from 8.5 atom % to 9.5 atom %, and a content of B is from 10.5 atom % to 11.5 atom % when a total content of Fe, Si, and B is 100.0 atom %.
 6. The amorphous alloy ribbon according to claim 1, which is produced by a single-roll method. 